Thanks for playing, I'm glad you enjoyed it!
I never actually finished God Hand, but I heard of counter hits recently while doing research on existing mechanics but never found the time to try going back to the game (got filtered by one of the early bosses back when I first tried it lmao). Parries have a strength level to them which dictates whether or not you get interrupted. Most attacks are around level 2 or 3, and you only get interrupted if your level is lower. This works both ways, and the intent of it was so you could exploit longer combo chains by parrying multiple attacks for more damage by drawing instead of only being able to parry one hit and breaking the whole combo. The charged attack inputs and the leniency in combo input windows was meant to allow players to be able to delay and time their own combos to match up with the parry timings without having to stop attacking, but in practice this is too difficult to pull off (even for me)
Parries in their current state are extremely strong, but I'm not sure where to put it as far as the difficulty risk/reward curve goes. Some types of parries are very difficult, and they should be rewarding if you pull them off, but waiting for a specific attack you know you can parry shouldn't become the degenerate strategy. (Although I'm perfectly fine if someone is able to parry literally every single attack in a row without stopping because that's the most extreme level of learning the boss. Can't say I'll be able to make it totally possible, but I would like to see someone try. )
It's somewhat of an oversight that you can damage them while they're knocked down, but it actually affects the player as well since they're using the exact same code. (However, the player is able to dodge out of it while the AI does not.)
I still have a lot to learn when it comes to animating, but I'll try adjusting the speeds a bit more to make it feel different. Poise is a very problematic function to design around, because it's really hard to convey to the player without just showing a number, and it gets even worse when it's modified in any way. In the current build, Louise has 25 poise in base form and 50 when transformed, and most player attacks deal 10 poise damage, which means it goes from ~3 attacks to flinch to 5 when transformed, but I doubt anyone could figure that out exactly just from playing. I think some passive poise is necessary to prevent stunlocks, and there are some active poise (super armour) actions in the game already, but doubling it to 50 was probably too much considering how sensitive this mechanic's numbers can be to change.
Could you elaborate on the part on responsiveness? Is this about the landing animation from the jump taking too long, or the step dodge being too short, or something about sprinting? I haven't played an Ys game, so I'll see if I can try it sometime soon to see what you mean.